Anticorrosive pigment composition and water-based anticorrosive coating material containing the same

Abstract

An anticorrosive pigment composition containing neither any heavy metal harmful to the environment nor zinc, which may be harmful to the environment. The composition is a product of the reaction of (a) aluminum dihydrogen tripolyphosphate, (b) a calcium compound selected among oxides, hydroxides, and carbonates, and (c) a magnesium compound selected among oxides, hydroxides, and carbonates. The composition exerts no adverse influence on the storage stability of water-based anticorrosive coating materials.

1. An anticorrosive pigment composition comprising
 (a) aluminum dihydrogen tripolyphosphate, 
 (b) 0.05 to 5.0 parts per 1.0 parts by weight of (a) of calcium hydroxide, and 
 (c) 0.01 to 1.0 parts per 1.0 parts by weight of (a) of magnesium oxide, said component (b) and (c) having reacted with said component (a) at least in part so that the pigment may be incorporated into a water-based anticorrosive paint formulation without compromising the storage stability thereof. 
 
     
     
       2. The anticorrosive pigment composition according to  claim 1  wherein the amount of said component (b) is 0.1-1.5 parts per 1.0 parts by weight of said component (a), and wherein the amount of said component (c) is 0.05 to 0.3 parts per 1.0 parts by weight of said component (a). 
     
     
       3. A process for producing an anticorrosive pigment composition comprising the steps of:
 reacting (a) aluminum dihydrogen tripolyphosphate, (b) calcium hydroxide and (c) magnesium oxide together in water at a weight ratio (b)/(a) from 0.05 to 5.0 and a weight ratio (c)/(a) from 0.01 to 1.0 at a temperature between 50° C. and 100° C. for a period of time at least 30 minutes; 
 removing water from the reaction mixture by filtration; and 
 drying and pulverizing the filter cake. 
 
     
     
       4. The process according to  claim 3  wherein aluminum dihydrogen tripolyphosphate is added to an aqueous slurry of calcium hydroxide in the first step and magnesium oxide is added thereafter. 
     
     
       5. The process according to  claim 3  wherein aluminum dihydrogen tripolyphosphate is added to an aqueous slurry containing both calcium hydroxide and magnesium oxide in the first step. 
     
     
       6. A water-based anticorrosive paint comprising an effective amount of the pigment composition of  claim 1  in an aqueous solution, emulsion or dispersion of a film-forming resin.